The objective of this project is to characterize factors which affect the in vivo clearance, breakdown and tissue localization of circulating DNA. DNA of various molecular weights will be isolated, and the clearance kinetics and tissue localization of these fragments will be studied. In order to localize antigenically intact DNA which has deposited in tissues (kidney and liver), tissue sections will be stained with fluorescein labelled anti-DNA antibodies. These anti-DNA antibodies will be isolated from the sera of patients with systemic lupus erythematosus by affinity chromatography. In addition, these antibodies will be used to synthesize DNA anti-DNA immune complexes in vitro, and the clearance and localization of these immune complexes will be studied. Experimental Animals: Mice.